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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Lokalizace objektů v bezdrátové komunikační síti na bázi WiFi / Location Estimation of Objects in WiFi Communication Network

Kohoutek, Jan January 2019 (has links)
The purpose of the thesis is to design and physically implement a system for location of devices in a Wi-Fi based networks deployed in the interior of small and medium-sized enterprises. First of all, the attention is given to the survey of commonly available technologies suitable for determination of the object position. Then, based on these findings, architecture of a location system comprising an array of sensor nodes and central processing unit is proposed. In conclusion, the results are presented and the fulfillment of the requirements is evaluated.
42

Étude de l'Urbanisation des Accès Virtuels et Stratégie de Métamorphose de Réseaux / Study of virtual access points urbanization and network metamorphosis strategies

Stiti, Oussama 15 December 2015 (has links)
La virtualisation, originalement introduite dans les réseaux pour en réduire les coûts de maintenance et de déploiement, a connu une explosion fulgurante remodelant le paysage des réseaux informatiques et télécoms. La virtualisation permet la mutualisation des ressources physiques pour instancier des machines virtuelles complétement isolées mais puisant leurs ressources du même matériel physique. Plus récemment le NFV (Network Functions Virtualisation) est apparu, et a permis de virtualiser des classes entières de fonctions de nœud de réseau dans des blocs qui peuvent se connecter pour créer des services de communication. Cette thèse s’inscrit dans ce contexte pour virtualiser les nœuds des réseaux d’accès, à savoir les points d’accès Wi-Fi. Le Wi-Fi est devenu la technologie de tous les enjeux pour les opérateurs mobile. Cette technologie leur permet notamment d’y délester une partie du trafic de données clients via des hotspots. Le problème qui se pose dans un tel mécanisme est que les normes Wi-Fi existantes ainsi que les logiciels de gestion de connexion d’un appareil mobile n’ont pas été développés dans l’optique du hotspot. A cet effet, la norme Hotspot2.0 a été créée, pour rendre l’expérience Wi-Fi similaire à celle du cellulaire en termes d’itinérance, de transparence et de sécurité. Nous avons dans nos travaux, appliqué le concept de NFV en virtualisant ces points d’accès Wi-Fi de nouvelle génération. La problématique face à laquelle nous avons été confrontés est la forte sécurité imposée par de tels dispositifs exigeants notamment l’enregistrement et l’installation de certificats de sécurité clients dans les lieux publics. Dans notre thèse nous proposons une architecture innovante permettant le rapatriement de ces éléments de sécurité à travers des bornes NFC. Ces mêmes bornes, dans une volonté d’urbanisation des points d’accès, permettront aux utilisateurs de créer leurs propres points d’accès Wi-Fi virtuels à la volée. Enfin, le dernier aspect de cette thèse touche à la problématique de gérance des entités virtualisées changeant les schémas de communication des réseaux traditionnels. Dans ce contexte, SDN (Software Defined Network) a émergé dans les datacenters pour redéfinir la façon de penser les réseaux plus en adéquation avec le contexte virtualisé. Cette thèse reprend le SDN pour l’appliquer en périphérie de réseaux sur les points d’accès Wi-Fi virtuels que nous avons créés. Plus qu’un nouveau paradigme de communications réseaux, nous verrons que l’introduction des concepts NFV/SDN aux réseaux Wi-Fi permettra dans un avenir proche de rendre les réseaux Wi-Fi plus souples, plus ouverts et plus évolutifs. / Virtualization was originally introduced in networks to reduce maintenance and deployment costs. It has experienced tremendous growth and reshaped the landscape of IT and ITC networks. Virtualization permits the sharing of physical resources for instantiating isolated virtual machines despite the fact that it is drawing its resources from the same physical hardware. More recently NFV (Network Functions Virtualization) appeared, it allows to virtualize entire classes of network functions node in blocks that can connect to create communication services. In this thesis we virtualize the access network nodes, namely Wi-Fi access points. The Wi-Fi became one of the hot-topic technology for mobile operators, it allows them to offload some of the customers’ data traffic via hotspots. The problem that arises in such a mechanism is the existing wireless standards, and mobile devices connection management software have not been developed for this purpose. The Hotspot2.0 standard was created to overcome this limitation, by making the Wi-Fi experience similar to the cellular in terms of roaming, transparency and security. We have in our work, applied the concept of NFV by virtualizing these brand new Wi-Fi access points. One of the problems that we faced is the high security required by such standard, including the provisioning of client credentials in public areas. In our thesis we propose an innovative architecture for the repatriation of these credentials through NFC terminals. These same terminals will be used for access points’ urbanization by allowing users to create their own Wi-Fi virtual access point on the fly. The last aspect of this thesis is related to the management of virtualized entities changing communication patterns of legacy networks. In this context, SDN (Software Defined Network) emerged in data centers to redefine the way we think about networks, and is designed for virtualized environments. In this thesis we brought SDN to the edge of the network in our Wi-Fi virtual access points. More than a new paradigm of networks communications, we will see that NFV/SDN in Wi-Fi networks will in the near future make Wi-Fi networks more flexible, open and scalable.
43

Predicting home Wi-Fi QoE from passive measurements on commodity access points / Prédiction de la QoE de la Wi-Fi domestique avec mesures passives sur les points d'accès de base

Hora, Diego Neves da 27 April 2017 (has links)
Une mauvaise qualité Wi-Fi peut perturber l'expérience des utilisateurs domestiques sur Internet, ou la qualité de l'expérience (QoE). Détecter quand le Wi-Fi dégrade la QoE des utilisateurs est précieux pour les fournisseurs d’accès internet (FAI), surtout que les utilisateurs tiennent souvent pour responsable leur FAI lorsque leur QoE se dégrade. Pourtant, les FAI ont peu de visibilité au sein de la maison pour aider les utilisateurs. Cette thèse conçoit et évalue des techniques de surveillance passive de la qualité Wi-Fi sur les points d'accès de base (APs) et prédit quand la qualité du Wi-Fi dégrade la QoE de l'application Internet. Nous concevons et évaluons une méthode qui estime la capacité de liaison Wi-Fi. Nous concevons et évaluons prédicteurs de l'effet de la qualité Wi-Fi sur la QoE de quatre applications populaires: la navigation sur le Web, YouTube, la communication audio et vidéo en temps réel. Nous concevons une méthode pour identifier les événements qui traduisent une mauvaise QoE pour identifier les cas où les prédicteurs QoE estiment que toutes les applications visées fonctionnent mal. Nous appliquons nos prédicteurs aux métriques Wi-Fi collectées sur une semaine de surveillance de 832 points d’accès de clients d'un grand FAI résidentiel. Nos résultats montrent que la QoE est bonne sur la grande majorité des échantillons, mais nous trouvons encore 9% des échantillons avec une mauvaise QoE. Pire, environ 10% des stations ont plus de 25% d'échantillons dont la QoE est médiocre. Dans certains cas, nous estimons que la qualité Wi-Fi provoque une QoE médiocre pendant de nombreuses heures, bien que dans la plupart des cas ces événements soient courts. / Poor Wi-Fi quality can disrupt home users' internet experience, or the Quality of Experience (QoE). Detecting when Wi-Fi degrades QoE is valuable for residential Internet Service Providers (ISPs) as home users often hold the ISP responsible whenever QoE degrades. Yet, ISPs have little visibility within the home to assist users. This thesis designs and evaluates techniques to passively monitor Wi-Fi quality on commodity access points (APs) and predict when Wi-Fi quality degrades internet application QoE. Our first contribution is the design and evaluation of a method that estimates Wi-Fi link capacity. We extend previous models, suited for 802.11a/b/g networks, to work on 802.11n networks using passive measurements. Our second contribution is the design and evaluation of predictors of the effect of Wi-Fi quality on QoE of four popular applications: web browsing, YouTube, audio and video real time communication. Our third contribution is the design of a method to identify poor QoE events. We use K-means clustering to identify instances where the QoE predictors estimate that all studied applications perform poorly. Then, we classify poor QoE events as short, intermittent, and consistent poor QoE events. Finally, our fourth contribution is to apply our predictors to Wi-Fi metrics collected over one week from 832 APs of customers of a large residential ISP. Our results show that QoE is good on the vast majority of samples of the deployment, still we find 9% of poor QoE samples. Worse, approximately 10% of stations have more than 25% poor QoE samples. In some cases, we estimate that Wi-Fi quality causes poor QoE for many hours, though in most cases poor QoE events are short.
44

Wi-Fi fingerprinting as a mean to measure building occupancy : A case study in an office environment

Bexhorn, Johan, Kvarnefalk, Karl January 2023 (has links)
The task of collecting visitor data in an indoor environment and therein determining the occupancy of a building is an extensive task. Conventional methods are expensive, time-consuming, and often lack the ability to produce data in longer time series. Further, they often require disruption of the studied area as equipment must be deployed. The use-case for such data sets is often also limited as it can only reflect a certain state-of-time in the studied space.The thesis seeks to investigate if using a Wi-Fi tracking system as a methodology to measure building occupancy through passive data collection is a viable method. Through continuous monitoring over an extended period, it seeks to do a trend analysis over a limited time. The collected data reveals insights into peak usage periods and commonly used areas. Although not used in this study, this methodology could leverage existing Wi-Fi infrastructure eliminating the need of installing additional equipment.In the case study, temporary wireless access points were deployed in the office which was studied. Data was then gathered after a month-long measurement period. This data was analyzed, and patterns were discovered showing higher occupation in the beginning of weeks and declining towards weekends. The focus of the study was to see if the technology would work in this context as it had previously not been tested in office environments.The results showed that there were some differences between data predicted by the Wi-Fi tracking system and that observed by the authors while conducting manual counts for validation during certain hours in the office. This may stem from faulty calibration of the model or settings affecting the signal strength required for the system to register devices as visitors. Mainly the conclusions are bound to the thesis subject and not placed in a larger context, however applications in public transport are suggested.The study displays the possibilities offered by using Wi-Fi tracking systems as a method to collect and analyze data in indoor environments. Further study of the subject would likely find a better model calibration able to predict more accurate results. Such results could be used and integrated with HVAC control systems to contribute to energy savings.
45

Integrating Wireless Sensor Technologies into Instrumentation and Telemetry Systems

Araujo, Maria S., Moodie, Myron L., Willden, Greg C., Thibodeaux, Ryan J., Abbott, Ben A. 10 1900 (has links)
ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / Recent technological advancements in low-power, low-cost, small-footprint embedded processors, sensors, and radios are resulting in the very rapid growth of wireless sensor network deployments. Wireless sensor networks merge the scalability and distributed nature of networked systems with the size and energy constraints of remote embedded systems. With the ever increasing need to develop less intrusive, more scalable solutions for instrumentation systems, wireless sensor technologies present several benefits. They largely eliminate the need for power and network wiring, thus potentially reducing cost, weight, and deployment time; their modularity provides the flexibility to rapidly change instrumentation configurations and the capability to increase the coverage of an instrumentation system. While the benefits are exciting and varied, as with any emerging technology, many challenges need to be overcome before wireless sensor networks can be effectively and successfully deployed in instrumentation applications, including throughput, latency, power management, electromagnetic interference (EMI), and band utilization considerations. This paper describes some approaches to addressing these challenges and achieving a useful system.
46

Styrning av datorers strömlägen med enhetsigenkänning via trådlösa nätverk : Controlling computer power modes using device recognition via wireless networks

Klintström, Angelica, Badini, André January 2015 (has links)
Rapportens syfte är att påvisa möjligheten att sänka energiförbrukningen på arbetsplatser. I samband med detta arbete utvecklas en hårdvarulösning, som kallas AutoSleep, vars syfte är att automatisera arbetsdatorns byte mellan strömspar- och aktivt läge.AutoSleep utför sin uppgift genom att söka efter en specifik förutbestämd enhet bland de enheter som för stunden är uppkopplade mot arbetsplatsens nätverk. Beroende på om enheten hittas eller ej skickar AutoSleep en signal till datorn som därefter antingen försätter datorn i strömsparläge eller i aktivt läge. För att undersöka nyttan och nödvändigheten hos arbetet utfördes en kvalitativ litteraturstudie, sammanställning av statistik från två enkäter, en intervju och en experimentell studie. All insamlad teori och statistik jämfördes med tidigare studier för att avgöra rapportens tillförlitlighet. Resultatet visade att det finns ett stort utrymme för förbättring inom energieffektiviseringen vid användandet av arbetsdatorer. Det system som utvecklades i samband med arbetet kan på ett enkelt sätt bidra till en energismartare arbetsmiljö. Arbetet visar på en möjlig lösning och använder ett hårdvarugränssnitt som endast är tillgängligt på stationära datorer. Hårdvarulösningen använder en smartphone som verktyg för enhetsigenkänning och växlar endast datorns strömläge mellan strömspar- och aktivt läge.
47

Telemetry System Architecture for a Solar Car

Walter, Eric, Glover, Nicholas, Cureton, Jesse, Kosbar, Kurt 10 1900 (has links)
ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV / This paper discusses the telemetry system used to monitor the performance of a solar-powered vehicle during testing and competitions. Car-side systems collect and transmit data onboard over an ISO 11898 / CAN bus. A bridge then converts this data into TCP/IP packets, which are transmitted via Ethernet to a Wi-Fi access point. The data is distributed through an IEEE 802.11N 5GHz mesh network to provide real time data to remote computers running telemetry software. This software displays and logs data from the car, allowing team members to monitor the vehicle.
48

The preparation and properties of nanocrystalline soft magnetic materials

Parmar, Baljit Singh January 1997 (has links)
No description available.
49

DIG

Neale, Spencer, III 09 May 2011 (has links)
DIG Spencer Kellogg Neale III MFA, Virginia Commonwealth University, 2011 BA, The College of Santa Fe, 2009 A thesis submitted in partial fulfillment of the requirements for the degree of Master of Fine Arts at Virginia Commonwealth University Virginia Commonwealth University, 2011 Major Director: Bob Paris Associate Professor, Department of Kinetic Imaging This paper is an outline to various creative pursuits in the Graduate school of arts at Virginia Commonwealth University in leading to my MFA Thesis Exhibition. I have been focused on the works of artists exploring audio/visual textures and overall conceptuality behind a Lo Fidelity sensibility. In my practice, I work through unconventional recording and editing techniques in an effort to define an individual sound within the music I make. With video, I have worked with software programs to manipulate and distort, altering the frame in an attempt to bend the very fabric of the medium. I also present a brief history of the Lo Fidelity aesthetic in music and film.
50

Kosmické inspirace v umění, architektuře a designu 60. let / Art, architecture and design in the space age

Wollner, Jan January 2011 (has links)
Cosmic inspiration influenced huge amount of different artistic material. It was the only one topic, which went through categories such as high art and popular culture, fine and applied arts, all the medias, official and independent production, state ideology and interest of common man. Thesis tries to go through these categories high and low, fine and applied, official and independent. It divils its material into thematic chapters to achieve this goal. First of them Expand your mind deals with projects of visionary architecture, which does not try to create new "cosmic" kapes but expand - with Marshall McLuhan -man's mind and senses. Then Gravitationless state describes petting loose of Earth as principal feeling of space age. Peace and Freedom play role of contradictory ideological terms to fights between politicians, artists and spaceships. How Does Space Look Like is a question for representation of cosmic topics between abstraction and realism ant the last charter Space for Children does not show reduced version of space for children but "adult" ideological construction of connection between the youngest generation and future in space. Individual chapters are preceded by theoretical introductin The World Where We Will Live Tommorow and The Word We Live In. It is a confrontation of...

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